The Big Kahuna

[Valoosj]

 
My first 'real' pedal project has started today. I did some easy stuff before, but this is the real deal. It's a real tube screamer, built by some Dutch guy that posted it on the guitar forum in the Netherlands. The soundclip was so awesome that I decided to build it. Three months later I began. Today that is 

This is the layout that I have in mind, the only thing that will change is the colour. Something like my looper pedal in the second pic



Preparation


Most of the wiring


The drilled enclosure. At the top, where the four holes are, I want to open up the whole top, and stick the tube through it


The tube


I'll post soundclips asap, as well as pics of the finished product.

[Dragonfly]

Nice !
I had a tremolo I built a few years back called the "Big Kahuna"
Keep us posted !

[snoof]

Is this a low voltage tube circuit, or is the tube for asthetics??

[Valoosj]

it's a 12AX7, running on 12V

[Valoosj]

the pedal is nearly finished. the troobleshooting has begin 

I have no idea on how to do this, are there any tips hint?

I tried going over the circuit with an Ohm/Voltage measure thingie. Leaving the - stick at the negative current pole, and going over the diode in the beginning, current drops from 12V to 0 V after the diode, is this normal? 

[snoof]

how is the diode used??  schematic??  I think you mean voltage drops to 0v.

[Valoosj]

Indeed, Voltage dropped to zero

here's the schematic
http://www.dirk-hendrik.com/temp/rn_tubedrive.pdf

[Valoosj]

If you follow on the schematic, I can find the 12V until I enter the tube through lug 4, and it goes out by lug 9, then it stops. lug 9 isn't connected to anything as far as I can see

[anchovie]

Are the heaters in the tube glowing orange?

[Valoosj]

Right now the 2 leds are on, and in bypass I get a guitar signal. when the screamer is on, no sound. the tube is warming up

[MarcoMike]

V drops from 12V to 0 V after the diode, is this normal?

no, it's not. check the diode polarity... no,  check your supply polarity first. then if it is ok just jumper the diode (which is probably reversed) and see if it works
then, lug 9 of the tube should have a lower voltage than lug 4 (or 5)

[Valoosj]

Right now the 2 leds are on, and in bypass I get a guitar signal. when the screamer is on, no sound. the tube is warming up

This is the current status marcomike. the Diode has been reversed.

[anchovie]

You need to be able to check the audio path as well as DC voltages. Use an oscilloscope or make an audio probe.

Starting at the input, trace the audio path through the circuit against the schematic and find the first point at which there is no guitar signal when there should be.

[snoof]

Just to confirm, Pin4 should be 12v, pin5 should go to ground, and pin9 NC for the heaters.  Is this how you have it wired??

[Valoosj]

the orientation of the transistor was wrong on the schematic!
I turned it around, and I have sound. The only problem is that the volume is really low, eventhough all pots are turned to maximum.
The sound sucks off course.
does anybody have an idea?

[petemoore]

 We gots lots of em.
  I'd start with the voltages, like all the VCC's and vbiases, opamp pins.
  then I'd try around the tube too, audio probing from input toward middle, or signal injecting from output toward input, trying along the signal path at accessible points, looking for where signal
isn't dropping out [passing through buffer stage and or...
  is getting gained up [passing through and increasing in volume through a turned up gain stage..
   or whatever..depending on the circuit conditions for each stage..what that  'would' produce.
  1B and 2B look like buffers, and that should produce unity gain across input to output when probing, the rest are gain stages, except not sure about the tube [gotta hit a new jam night spot after a shower here] except if the output is from the cathode it'd also be a buffer stage.